Frequency converter

ABSTRACT

The frequency converter for an electrical motor essentially consists of power part integrated in a common semiconductor compoent, of a component accommodating at least the intermediate circuit electronics and of a component accommodating the control and regulation electronics. The electrical connections from the semiconductor component of the power part to the intermediate circuit component and from the semiconductor component of the power part to the control and regulation component are formed by sheet metal connections which are positioned and mechanically connected to one another by way of a common cast body.

BACKGROUND OF THE INVENTION

[0001] The invention relates to a frequency converter for an electricmotor with the features specified in the introductory part of claim 1.

[0002] Frequency converters of this type are for example applied for thedrive of electric motors of pump units, fans and other machines. Whilstearlier a frequency converter application was exclusively considered formotors of more than 1 KW, with an increasing miniaturization of thefrequency converter and the manufacture on a large scale, theapplication also in the region between 50 W and 1000 W becomeseconomically practicle. In particular with pump units the application offrequency converters is particularly advantageous since with this, pumpunits may be provided which on account of the high rotational speedinspite of a relatively small diameter realize a large delivery flow.

[0003] A submersible unit for such a pump unit is for example known fromDE 197 27 202 A1. With such an arrangement all components of thefrequency converter are to be accommodated within a cylindrical housingof a comparatively small diameter. In contrast however to otherapplications with which the axial and radial constructional length ofthe motor where possible is not to be increased, one seeks to arrangethe components of the frequency converter in a flat manner on the outerperiphery of the motor housing. Again with other applications thefrequency converter where possible is to be accommodated in the terminalbox of the motor, thus on the rectangular-parallelpiped-shaped housing.Furthermore the construction is to be modified for the respectiveapplication such that the waste heat arising in the power part may bereliably led away.

[0004] Since the manufacturing costs of such a frequency converterdepend very heavily on the number of pieces to be manufactured, it isdesirable for different applications to be able to apply the samecomponentry or components. It is known to divide up the frequencyconverter into componentries and to arrange these individualcomponentries for example in a cicuitboard manner. Functionally afrequency converter consists of an input circuit, of an intermedatecircuit and of a power circuit—also called inverse rectifier—as well asof a control and regulation circuit. It is known to integrate the powercircuit of the frequency converter into a semiconductor component orinto a semiconductor element, to construct the input as well as theintermediate circuit on a common circuitboard as well as the control andregulation circuit on a further circuitboard. With this construction,particularly large construction components such as for examplecapacitors and coils of the intermediate circuit may be arrangedseparate from the circuitboard.

BRIEF SUMMARY OF THE INVENTION

[0005] Against this background it is the object of the invention todesign a frequency converter of the known type such that its applicationis even more versatile and its manufacture is even more economical.

[0006] This object is achieved according to the inventin by the featuresspecified in claim 1. Advantageous formations of the invention arespecified in the dependent claims, in the subsequent description and inthe drawings

[0007] The basic concept of the present invention is to integrate thelead connections and connections within the frequency converter wherepossible into one component, specifically into that of the powerpart—this comprises essentially the power circuit and where appropriatefurther power electronics such as for example the input circuit. Forthis the power part is particulary useful to be selected since the powerpart requires lead connections to the input circuit or to the mainssupply, to the intermediate circuit, to the control and regulationcircuit and to the motor. These electrical connections may all beintegrated into one component, wherein the leads are formed of sheetmetal sections, thus from punched sections which on the one hand areinexpensive to manufacture and on the other hand offer a high intrinsicstability and a sufficiently large conducting cross section. These leadslead directly to the circuitboards of the connection components, wherethey are contacted, be it by way of soldering or welding or also by wayof a plug-and-socket connection.

[0008] These components fixed together with the semiconductor componentby way of a cast mass are inexpensive to manufacture, and specificallywith a differing arrangement of the connections without having to changeanything on the basic design construction. Simultaneously theseadditional design elements may be used for fastening the semiconductorcomponent. The semiconductor component as a rule specifically requiresan intensive cooling, which usually is effected by a heat conductingbearing of this onto a heat distributor. Via the cast body which eitherencompasses the semiconductor component on at least three sides or alsoencloses it, be it partly or completely, there may be effected afastening, be it via clamping clips or screw closures, rivets orlikewise, without mechanically overloading the semiconductor component.

[0009] The semiconductor component containing the power part is usuallyrectangular-parallelpiped-shaped and flat, wherein the lead connectionsare led out at the narrow end-faces. With such a construction it isparticularly advantageous when the leads facing the intermediate circuitcomponent are led out to one side of the cast body or of thesemiconductor component, the leads facing the control and regulationcomponent to the opposite distant side of the cast body and the leadsfacing the motor to a side displaced by 90° to this. Disregarding thefact that this arrangement permits a crossing-free leading of the leads,thus a leading of the leads in one plane, this arrangement has theadvantage that the intermediate circuit component as well as the controland regulation component, according to application, may be arranged at adifferent angle to the power component. There may therefore for examplebe selected an arrangement with which these three components are adaptedto the curvature on the outer periphery of a motor. By way of abending-up about in each case 90° with respect to the power componentthere may also be achieved an arrangement which becomes essentiallyrectangular parallelpiped-shaped or is insertable into a cylindricalbody. With a straight arrangement in contrast it will result in atwo-dimensionally constructed frequency converter. Since the electricalconnections leaving the power part are formed by sheet metal sectionswhich usefully lie such that their flat sides lie parallel in the planeof the semiconductor component or parallel thereto, these may be bent uppractically in any manner along the sides of the power part component.As long as they in this region are encompassed by the cast body only thecast mould it to be correspondingly adapted or the bending up to becarried out before the cast body is completely solidified.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The invention is hereinafter described in more detail by way ofone embodiment example shown in the drawings. There are shown in:

[0011]FIG. 1 in a simplified perspective representation the design andarrangement of the sheet metal sections before the manufacture of thecast body,

[0012]FIG. 2 in the same representation the arrangement after themanufacture of the cast body, wherein the semiconductor component forthe purpose of overview is shown outside the cast body and

[0013]FIG. 3 in a schematic representation three possible arrangementsof the components of the frequency converter.

DETAILED DESCRIPTION OF THE INVENTION

[0014] The semiconductor element 1 shown schematically in FIG. 2comprises the usual rectangular-parallelpiped and two-dimensionalconstructional shape usual for such integrated components, with whichelectrical connections in the form of thin wires (not shown) are led outlaterally. The leads are connected by bonding, for example by ultrasoundwelding, to sheet metal sections 2 which have obtained theconstructional shape and arrangement shown in the FIG. 1 by way ofpunching and cold-forming.

[0015] As is deduced from the FIGS. 1 and 2 the sheet metal sections 2which simultaneously form electrical conductors are arranged in threegroups. There is a first group of in total eighteen sheet metal sections2 which are bent up by about 90° and extend to one side of thesemiconductor element 1. Lying opposite there is formed a further group4 of sheet metal sections which consists of three sheet metal sectionswhich likewise are bent up by about 90° out of the plane of thesemiconductor element 1, but in the opposite direction to those of thegroup 3. These sheet metal sections furthermore have a greater lengththan those previously mentioned. The group 5 finally which encloses thegroup 4 of sheet metal sections 2, consists of a pair of three sheetmetal sections which in each case are bent up twice by 90°, however inopposite diecrions, so that the free ends of the sheet metal sections ofthe group 5 extend in a plane located parallel to the semiconductorelement 1. Finally there are provided two sheet metal sections whichextend to the two other longitudinal sides of the semiconductor elementand have a purely mechanical function.

[0016] The groups 3, 4, 5 of sheet metal sections 2 as well as the twosheet metal sections 6 are positioned in a common cast body 7 andmechanically connected to one another. The cast body 7 encompasses inthe shown embodiment the semiconductor element 1 on all four sides sothat it is incorporated and protected by the cast body 7 in a frame-likemanner. The sheet metal sections 6 serve the fastening of the wholepower part component 8 formed in this manner. The cast body 7 consistingof plastic is not electrically conducting.

[0017] With the present embodiment form furthermore there is provided afurther cast body 9 which encompasses a part of the sheet metal sectionsof the group 4. This cast body 9 holds the sheet metal sections embeddedtherein in their position to one another and insulates themsimultaneously in this region from the surroundings. The group 4represents the connection leading to the motor which is to be activatedby the frequency converter. As is deduced from FIG. 2 the free ends ofthe sheet metal sections 2 of the groups 3 and 5 are designed in aslimline tapering manner so that they form the plug-side part of aplug-and-socket connection whose bushing-side part is arranged oncircuitboards, and specifically on a circuitboard 10 shown schematicallyin FIG. 3 and forming the control and regulation component as well as ona circuitboard 11 accommodating the intermediate circuit which may alsocomprise parts of the input circuit. This intermediate circuit componentis connected via the group 5 of the sheet metal sections 2 and likewisecomprises suitable receivers for the plugs formed by way of the sheetmetal sections 2 of the group 5.

[0018] The mechanical fastening of the whole power part component formedin this way is effected usefully via the lateral sheet metal sections 6such that the semiconductor component 1 bears directly on the heatdistributor in order to lead away the waste heat arising here.

[0019] The semiconductor element 1 which here is not described in detailcomprises at least the power electronics of the power part, in thepresent embodiment example however also the rectifier of the inputcircuit. The bending-up of the free ends of the sheet metal sectionsmay, as the finished cast shape according to FIG. 2 makes clear, be alsovaried after the casting by way of cold-deformation. It may also beenvisaged to correspondingly deform the sheet metal sections before thecasting, depending on the arrangement of the further componentries. Inany case with such a design of the power part there result numerouspossibilities of arranging the componentries to one another. In FIG. 3there are shown three possiblities of these by way of example. With theembodiment according to FIG. 3a the power component lies essentially inthe same plane as the intermediate circuit component 11 as well as thecontrol and regulation component 10 which are arranged to both sides ofthe power component 8. The lead connection to the motor is effectedperpendicularly thereto. With the embodiment according to FIG. 3b thecircuitboards of the control and regulation circuit 10 as well as of theintermediate circuit are arranged perpendicular to the power partcomponent 8, i.e. to the plane in which the semiconductor element 1lies. In this manner the frequency convertor may be arranged in arectangular-parallelpiped-shaped housing.

[0020] The arrangement according to FIG. 3c shows how the previouslymentioned three components 8, 10 and 11 may be arranged following theouter periphery of the motor housing 12. Also with this embodiment thelead connection is effected via the group 4 of sheet metal sections 2perpendicularly downwards to the motor.

[0021] As is to be deduced from these arrangements which are notconclusive and are to be understood only as an example, the power partcomponent 8 with its sheet metal sections 2 incorporated into aframe-like cast body 7 allows an inexpensive solution of the electricaland mechanical connection of the individual componentries.

List of Reference Numerals

[0022]1—semiconductor component

[0023]2—sheet metal sections

[0024]3—group of sheet metal sections to the control and regulationcomponent

[0025]4—group of sheet metal sections to the motor connection

[0026]5—group of sheet metal sections to the intermediate circuitcomponent

[0027]6—sheet metal sections for the fastening

[0028]7—cast body

[0029]8—power part component

[0030]9—cast body of the group 4

[0031]10—control and regulation part

[0032]11—intermediate circuit part

[0033]12—motor

1. A frequency converter for an electrical motor essentially consistingof a power part integrated in a common semiconductor component, of acomponent (intermediate circuit component) accommodating at least theintermediate circuit electronics and of a component (control andregulation component) accommodating the control and regulationelectronics, wherein the electrical connections from the semiconductorcomponent of the power part to the intermediate circuit component andfrom the semiconductor component of the power part to the control andregulation component are formed by sheet metal connections which arepositioned and mechanically connected to one another by way of a commoncast body and wherein the intermediate circuit component and the controland regulation component in each case comprise a circuitboard, and theleads of the power part which are formed by these sheet metal sectionsconnect to these circuitboards.
 2. A frequency converter according toclaim 1, wherein the leads leading from the semiconductor component ofthe power part to the motor are likewise formed by sheet metal sectionswhich are held in the cast body and connect to the motor.
 3. A frequencyconverter according to one of the preceding claims, wherein the castbody encompasses the semiconductor component at at least three sides. 4.A frequency converter according to one of the preceding claims, whereinthe cast body forms a mounting for the frequency converter.
 5. Afrequency converter according to one of the preceding claims, whereinfree ends of sheet metal sections form parts of plug-and-socketconnections to at least one connection component.
 6. A frequencyconverter according to one of the preceding claims, wherein the sheetmetal sections are formed by punching or laser cutting.
 7. A frequencyconverter according to one of the preceding claims, wherein the leadsfacing the intermediate circuit component are led out to one side of thecast body, the leads facing the control and regulation component are ledout to the opposite distant side of the cast body and the leads facingthe motor are led out to a side diplaced by 90° to this.
 8. A frequencyconverter according to one of the preceding claims, wherein the leadconnections of the semiconductor component are conductingly connected byway of welding to the sheet metal sections.